This application is the third renewal of the Midwest Sexually Transmitted Infections and Topical Microbicides Cooperative Research Center, a consortium agreement among Indiana University, Northwestern University and the University of Iowa. The overarching theme of the Midwest Center is epidemiology, acquisition, prevention and pathogenesis of STIs in young women. Our goals are to examine: (1) the acquisition of STIs in a cohort of adolescent and young adult women and the developmental factors that are associated with their use and acceptance of topical vaginal microbicides; (2) how HSV-2 and Neisseria gonorrhoeae gain access to human cells of the female genital tract, a prerequisite for the development of topical microbicides that block STI entry; (3) mechanisms underlying two sequelae of STIs, cervical cancer and acquisition and transmission of HIV. Of 5 projects, two center on STIs in a cohort of 14 to 24 year old women. Project will (1) focus on developmental factors influencing the acquisition of N. gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium and Trichomonas vaginalis in adolescents at high risk for STI as they enter young adulthood, (2) assess vaginal microbicide acceptability as a function of relationship status and different ages across adolescence and young adulthood, (3) seek to elucidate signaling pathways involved in internalization of gonococci by primary human cervical cells and will utilize clinical specimens from the adolescent cohort to confirm in vitro findings, (4) define the cell entry pathways used by HSV-2 to infect cells of the female genital tract and of the nervous system in a murine vaginal model of disease, and in human cervical cells. HSV-2 isolates obtained from the clinical cohort will be used to challenge vaccinated mice, (5) examine the role of the HPV E7 protein in cervical cancer by studying the interactions of E7 derived from low risk and high risk viruses with host proteins on the expression of S phase genes and cell cycle exit during differentiation, (6) perform experimental infections with Haemophilus ducreyi in human volunteers to address hypotheses about pathogenesis and about interactions between H. ducreyi and HIV that facilitate viral acquisition and transmission. The five projects will be supported by Biostatistical, Clinical and Laboratory Cores. The extensive collaboration and cross disciplinary fertilization which exists among the different projects will be reinforced by semiannual scientific meetings and by an external advisory board, which will assess progress of each project and provide constructive criticism and assistance.